Finding the origin in .laz file with LAStools

Question

I obtained a .laz file, which I used lasinfo and las2txt to view the records.

 Scale Factor X Y Z:          0.00100000000000 0.00100000000000 0.00100000000000
  Offset X Y Z:                22717.000 31027.000 21.000
  Min X Y Z:                   23776.000 30560.000 14.859
  Max X Y Z:                   23807.997 30591.999 43.696
  Spatial Reference:           
PROJCS["SVY21 / Singapore TM",
    GEOGCS["WGS84, WGS84",
        DATUM["unknown",
            SPHEROID["unnamed",6378137,298.257223563]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",1.366666666666667],
    PARAMETER["central_meridian",103.8333333333333],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",28001.642],
    PARAMETER["false_northing",38744.572],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]]]

and a sample record is 23776.000,30560.047,19.450.

Now, how do I interpret the above information, as in where is the origin in which the record referenced? When I punch in the lat, long from the above, I got the point below. If that is the origin and the X and Y is pointing eastwards and northwards respectively, then my assumption is incorrect, as I am certain that the data originated from somewhere southwest of that marker.

.

Answer 1

The sample record you show is in projected coordinates and the two values for longitude and latitude listed in the Coordinate Reference System (CRS) are part of the parameters that defined the projection that was used, here a particular Transverse Mercator projection that is called "SVY21 / Singapore TM" and is centered near Singapore. You can use the latest version of free and open source las2las from LAStools to convert from those projected coordinates to the longitude / latitude coordinates with this command line:

las2las -i sin.laz -epsg 3414 -target_longlat -o sin_longlat.laz